WO1999042501A2

WO1999042501A2 - Method for the production of polymers from n-vinyl compounds

Info

Publication number: WO1999042501A2
Application number: PCT/EP1999/000891
Authority: WO
Inventors: Roman Benedikt Raether; Wolfgang Paulus; Frank Braun; Klaus MÜLLEN; Markus Klapper; Marco Steenbock
Original assignee: Basf Aktiengesellschaft; MAX-PLANCK-Gesellschaft zur Förderung der Wissenschaften e.V.
Priority date: 1998-02-19
Filing date: 1999-02-11
Publication date: 1999-08-26
Also published as: JP2002504572A; ES2198901T3; KR20010041072A; WO1999042501A3; EP1054913A2; AU2926199A; DE19806853A1; DE59905187D1; BR9908087A; ATE238358T1; CA2320990A1; US6369165B1; EP1054913B1; CN1297459A

Abstract

The invention relates to a method for the production of polymers from N-vinyl compounds, characterized in that vinyl compounds are polymerized in the presence of radicals of general formula (I), wherein Q stands for NR2 or S and T stands for CR3R4 or S and R?1, R2, R3 and R4¿ can be identical to or different from each other and independently stand for hydrogen, C¿1?- to C20-alkyl or C6- to C18-aryl.

Description

Process for the preparation of polymers from N-vinyl compounds

description

The present invention relates to a process for the preparation of polymers from N-vinyl compounds. Furthermore, the present invention relates to the use of radicals for the production of polymers from N-vinyl compounds. In addition, the present invention relates to the polymers obtainable by the process according to the invention and their use.

A common process for the polymerization of N-vinyl compounds such as l-vinyl-2-pyrrolidone (N-vinylpyrrolidone, hereinafter NVP) or N-vinylformamide (hereinafter NVF) is radical polymerization. It also allows the N-vinyl compounds to be copolymerized with other monomers. However, because of unavoidable side reactions such as chain transfer, disproportionation, recombination or elimination, it is very difficult to control the molecular weight distribution. Polymers with a polydispersity index PDI of 2.0 or greater are normally obtained. PDI is defined as PDI = M _w / M _n , where M _{w is} the weight average and M _{n is} the number average molecular weight. The architecture and structure of the polymers is also difficult to influence.

For this reason, the so-called "controlled radical polymerization", which is sometimes also called "living radical polymerization", was developed for the production of polymers with a narrow molecular weight distribution and is described, for example, in M.K. Georges et al, Trends in Polymer Science, Vol. 2, No. 2 (1994), pages 66 to 72. The basic strategy of this method is to temporarily block the reactive radical chain ends of a growing polymer chain and to reactivate it again in a targeted manner (reinitiation). The dynamic balance between active and sleeping form leads to a low stationary concentration of free polymer radicals.

EP-A 135 280 describes the use of stable N-oxyl radicals which reversibly combine with the reactive chain ends. However, no high molecular weight polymers are obtained by this process, only oligomers.

A special group of initiators for controlled radical polymerization are compounds that can be split into radical initiators and N-oxyl radicals (trends in Polymer Science, 4 (6), 1996, 183-188). These compounds enable, for example, the construction of branched polymers. However, only selected monomers can be polymerized and the reaction temperatures are unsatisfactorily high.

In general, the reaction rates in the polymerization of monomers in the presence of N-oxyl radicals are too slow for many technical purposes. Therefore e.g. strong organic acids also used (US-A 5,322,912). However, these can cause difficulties when refurbishing the products.

DE-OS 195 16 967 describes processes in which vinyl monomers are polymerized in the presence of common radical initiators and electron donors which stabilize the radical chain end.

WO 94/18241 describes the polymerization of NVP with a number of initiators which have a different decomposition temperature. Such a regulation is cumbersome and the polymers obtained are not terminated with functional groups which can be used for reinitiation.

Matyjaszewski describes in Polym. Mater. Be. Eng., Vol. 76, pp. 147-148 (1997) the controlled radical polymerization of NVP by atom transfer radical polymerization (ATRP). However, heavy metals are required for the ATRP method. The reduction product poly-NVP is a good complexing agent for these heavy metals, which is why the poly-NVP produced by ATRP contains heavy metals and is therefore unsuitable for use in medicine.

Polymers that have been radically polymerized using a regulator can be converted into block copolymers by reinitiation in the presence of another monomer. Abadie describes in Eur. Polym. J., Vol. 26 (5), pp. 515-520 (1990) that block copolymers containing NVP can in principle also be obtained by changing the reaction mechanism. This process has the disadvantage that an additional reaction step is required compared to a purely radical process.

Turner revealed in Polym. Reprints (Am. Chem. Soc, Div. Polym. Chem.) (1988), Vol. 29 (2), pp. 6-7 the synthesis of a block copolymer from NVP and styrene, but in which the molar mass of the product is lower than that of the starting polymer. Munam Lee describes in J. Chem. Coc. Faraday Trans. 1, Vol. 74 (7), pp. 1738-1749 (1978) a controlled radical polymerization of NVP. However, the polymerization proceeds very slowly: after a reaction time of 40 hours, only "traces" of polymer are found.

Triazolyl radicals can also be used as regulators for the radical polymerization, as taught by the older, unpublished application DE-P 19636996.7. The application mentions vinyl aromatics, alkyl esters of acrylic acid and methacrylic acid, and acrylonitrile as preferred monomers. Homopolymers and statistical copolymers of N-vinyl compounds are not mentioned.

The object of the present invention was to provide a new process for the preparation of polymers containing N-vinyl compounds such as NVP and NVF which does not have the aforementioned disadvantages. Furthermore, the new process should allow very good control over both the molecular weight distribution and the architecture and structure of the polymers. In addition, a process should be found which has a sufficiently high reaction rate even at lower temperatures. The polymers obtained should be free of heavy metals so that they can be used in medicine. Furthermore, a process should be found which enables the preparation of block copolymers from blocks of N-vinyl compounds and blocks of other monomers in a simple manner without changing the reaction mechanism.

Accordingly, a process has been found for the preparation of polymers from N-vinyl compounds in which the polymerization of the N-vinyl compounds in the presence of radicals of the general formula

I.

^ \

¹ (I)

in which Q is NR ² or S and T is CR ³ R ⁴ or S and R ¹ , R ² , R ³ and R ^{4 can be} identical or different from one another and independently of one another hydrogen, Ci to C ₂ o ~ alkyl or C ₆ - until C ₁₈ aryl is carried out. According to the invention, the radicals represented in the general formula I are also to be understood as meaning their tautomers and positional isomers. The alkyl radicals can be linear, branched or cyclic. They can be both unsubstituted and substituted, for example with one or more halogen atoms, such as chlorine, nitrile groups, N0 ₂ , sulfonic acid residues, hydroxyl groups, alkyl or aryl ester residues. In addition, the alkyl radicals can contain sulfoxide or carbonyl radicals. The alkyl radicals include C 1 -C ₁ -alkyl, preferably C 1 -C 1 -alkyl, for example methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl , Cyclopentyl, n-hexyl or cyclohexyl. Among them, methyl is particularly preferred. The preferred aryl radicals include phenyl, naphthyl and biphenyl. The aryl radicals can either be substituted by one or more substituents or unsubstituted. Suitable substituents are alkyl radicals, for example C 1 -C 10 -alkyl, preferably C ₁ -C ₆ -alkyl, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl or t-butyl or else hydroxyl groups or halogen atoms how chlorine is considered. Furthermore, the aryl radicals can also be substituted with one or more halogen atoms, such as chlorine, nitrile groups, NO ₂ , sulfonic acid radicals, alkyl or aryl ester radicals. Phenyl is particularly preferred among the aryl radicals.

Examples of suitable radicals I are thiatianolyls of the general formula

or dithiadianolyls of the general formula

2,5-Dihydro-1H-1,2,4-triazol-2-yl radicals (triazoyl radicals) of the general formula are preferred

Triazolyl radicals whose radicals R ³ and R ^{4 are} identical are particularly preferred. In the very particularly preferred triazolyl radicals, R ^{1 is} phenyl, R ² phenyl or methyl and R ³ and R ^{4 are} each phenyl, biphenyl-2, 2'-diyl, 6, 6 '-dimethylbiphenyl-2, 2' - diyl or 5 5,5'-dimethylbiphenyl-2, 2'-diyl.

2,5-dihydro-1H-1,2,4-triazol-2-yl radicals are known per se or can be obtained by methods known per se. For example, the triazolyl radicals are irradiated by

10 1H-1, 2, 4-triazoles accessible with γ-radiation or can be prepared by dehydrogenating 4, 5-dihydro-1H-1, 2, 4-triazoles with a basic solution of potassium α-hexacyanoferrate. Another method to obtain triazolyl radicals is the ring narrowing of tetrazines in the presence of acids (Tetrahedron, 51 (47),

15 1995, 12883-12898).

Thiatrianolyls are e.g. can be obtained by reducing the corresponding thiotriazole-1-ium salts (J. Am. Chem. Soc. Perkin Trans 2 (1990) 1619). Dithiadianolyls are e.g. can be obtained by reducing the corresponding dithiadiazadium salts (Chem. Ber. 118 (1985) 3781.

The radicals I can be generated in situ, for example, by one of the abovementioned methods. The radicals are preferred

25 I manufactured separately, isolated and used as such. In addition, the radicals I can also be used in the process according to the invention in the form of compounds II which can be split into radical initiators and radicals I. Such compounds can, for example, under the general formula

30 II can be summarized

_R 5— NT ₍ II ₎

\ / ³⁵ C— N

/ R ^l

in which R ^{5 stands} for a radical which, when split off, can initiate a radical reaction. Preferred compounds II contain as R ⁵ alkyl, preferably Ci to C biso alkyl, where the alkyl radical can be both linear and branched and can be substituted by one or more substituents, in particular halogen atoms, such as chlorine, or nitrile groups. The alkyl radicals 45 can also be interrupted by one or more heteroatoms such as oxygen. R ⁵ can also be an aryl or substituted aryl radical, preferably C ₆ to C ₁₈ aryl. Preferred radicals R ⁵ are Residual decomposition of commercially available radical initiators such as isobutyronitrile or benzoyl.

The preparation of compounds II can e.g. by reacting a radical source such as dibenzoyl peroxide or azodiisobutyronitrile with a radical I. The radical source can be split into the decay residues by methods known per se, for example thermally, photochemically or redorchemically.

The compounds II can be cleaved, for example, thermally or photochemically. Furthermore, the compounds II can be cleaved by redox chemistry. As a rule, the compounds II are split thermally. In general, the compounds II cleave at temperatures in the range from 0 to 300 ° C., preferably in the range from 50 to 150 ° C.

The process according to the invention can be carried out by using a radical I or a compound II. It is also possible to use different radicals I or compounds II. It is also possible to use mixtures of radicals I and compounds II.

With the method according to the invention, N-vinyl compounds can be converted into polymers. Preferred N-vinyl compounds are 1-vinyl-2-pyrrolidone (= N-vinylpyrrolidone, NVP) and N-vinylformamide (NVF). N-vinyl pyrrolidone is very particularly preferred.

Unless they are used in the form of a compound II, the radicals I are generally unable to initiate a polymerization reaction. Therefore, according to one of the preferred embodiments, radical initiators can also be used. The radical initiators are known per se and are described, for example, in Ullmann's Encyclopedia of Industrial Chemistry, 4th edition, volume 15, page 187. Are particularly suitable

Peroxides such as dibenzoyl peroxide and cumene hydroperoxide and especially diazo compounds such as azodiisobutyronitrile (AIBN). Mixtures of different radical initiators can also be used.

The molar amount of radical initiator can be 10 " ⁶ to 1 mol / 1, preferably 10" ⁴ to 10 ^"1 mol / 1, based on the volume of the monomers used. The molar ratio of radical initiator to radical I is that Rule from 1: 0.5 to 1:10, preferably from 1: 0.5 to 1: 5, in particular from 1: 0.5 to 1: 2.5. _Fter a further preferred embodiment, electron donors, such as are described for example in DE-OS 195 16 967 be used. Phenothiazine derivatives or phenoselenazines of the general formulas are preferred _electron donors

or

in which

X represents oxygen, sulfur or selenium, preferably sulfur

and

R ^{6 is} a hydrogen atom, -C 1 -C ₅ -alkyl, preferably methyl or ethyl, -CF ₃ , halogen, preferably -CI, -CN, alkyl sulfide, preferably C ₃ -C 10 -alkyl sulfide, aryl sulfide, preferably phenyl sulfide , alkoxy, preferably Ci to Cio alkoxy, aryloxy, preferably phenoxy, alkylamine, preferably Ci to C ₁₀ alkylamine, dialkylamine, preferably di-Ci to Cio alkylamine, arylamine, preferably phenyl amine, diarylamine, preferably diphenylamine.

R ^{7 is} a hydrogen atom or 4Z-Z ¹ ,

Z for an unbranched or branched Ci to C ₂₅ alkylene group, preferably a Ci to C ₅ alkylene group, particularly preferably a Ci to Cio alkylene group, for example

Methylene, ethylene, 2-methyl-ethylene, n-propylene or n-butylene,

Z ¹ -OH, alkoxy, preferably Ci to Cio alkoxy, aryloxy, preferably phenoxy, alkyl sulfide, preferably Ci to -C ₀ alkyl sulfide, aryl sulfide, preferably phenyl sulfide, -NH ₂ , alkylamine, preferably Ci to Cio alkylamine , Dialkylamine, preferably di-ci- bis Cio -alkylamine, arylamine, preferably phenylamine, diarylamine, preferably diphenylamine or Z ² , of which Z ² , -NH ₂ , alkylamine or dialkylamine are preferred,

Z ^{2 is} a C ₄ - to C -cycloaliphatic radical, preferably a C ₅ - or Cg-cycloaliphatic ring, which has one or more -O-, -S- or -N (alkyl) groups, preferably -N (Cι- bis Cio -Alkylamin) may contain, the latter group is preferred and Z ² is linked via a carbon atom to Z and the groups -O-, -S- and -N (alkyl) - are not directly connected to each other.

The preferred phenothiazines include:

CH ₃

(CH ₂ ) NN - H

where r is an integer from 2 to 11 and s is an integer from 1 to 4.

Mixtures of different electron donors can also be used.

The compounds used as electron donors are known per se or can be prepared by processes known per se and are described, for example, in J.H. Perlstein, Angew. Chem. Int. Ed. Engl. 16 (1977), pages 519 to 534 and M.R. Bryce, Aldrichimica Acta, Vol. 18 (1985), pages 73 to 77.

The molar ratio of electron donors to radicals I can be in the range from 0.1: 1 to 10: 1, preferably from 0.5: 1 to 2: 1.

The molar ratio of electron donors to radical initiators can be in the range from 1: 1 to 3: 1, preferably 1.6: 1 to 2.4: 1.

The process according to the invention can also be carried out in the presence of mixtures of the radicals I and N-oxyl radicals. It is also possible to carry out the process according to the invention in the presence of mixtures of radicals I, electron donors and N-oxyl radicals. The N-oxyl radicals serve as moderators, i.e. they slow down the reaction rate.

As already mentioned at the beginning, N-oxyl radicals are known per se or they can be prepared by methods known per se. According to the invention, different structures of N-oxyl radicals can be used. This includes both N-oxyl radicals of acyclic and cyclic structure. As a rule, cyclic N-oxyl radicals of the general formula IV are preferred:

0

The radicals R ⁹ to R ¹⁴ may be the same or different from one another and are independently hydrogen, C ₁ -C ₂ -alkyl, C ₆ -C ₈ -aryl, -OH, -SH, -NH ₂ , alkylamine or Dialkylamine. The variable n represents an integer from 1 to 5, preferably 2 or 3. Among the alkyl radicals, C 1 -C 4 -alkyl, in particular C _x - to C ₅ alkyl, and phenyl among the aryl radicals are preferred. The radicals R ⁹ and R ¹⁰ and R ¹³ and R ^{14 are} each preferably phenyl or alkyl or a phenyl radical and an alkyl group such as methyl or ethyl. R ¹¹ and R ¹² are preferred ^¬ What serstoff. If n is greater than 1, the CR ^ R ¹² groups can be the same. However, different CR ^{1: L} R ¹² groups can also be present. If there is more than one CR ^{1: 1} -R ¹² group, the residues of one of these groups preferably denote OH and hydrogen.

Preferred are 2, 2, 6, 6-tetramethyl-1-piperidinyloxy (TEMPO), 4-0x0-2.2, 6, 6-tetramethyl-1-piperidinyloxy (4 -Oxo-EMPO), 4 -hydroxy-2, 2,6,6-tetramethyl-1-piperidinyloxy, 2,2,5,5-tetra-methyl-1-pyrrolidinyloxy, 3-carboxy-2, 2,5,5-tetramethyl-pyrrolidinyloxy and di-tert. -butyl nitroxide. 2, 6 -Diphenyl -2, 6 -di - methyl-1-piperidinyloxy and 2, 5 -diphenyl -2, 5 -dimethyl-1-pyrrolidinyloxy can also be used. Mixtures of different N-oxyl radicals can also be used.

The molar ratio of N-oxyl radical and radical I is generally in the range from 0.1: 1 to 20: 1, preferably in the range from 0.1: 1 to 10: 1, particularly preferably in the range from 0.1: 1 up to 2: 1.

The molar ratio between the N-oxyl radical and the radical starter is preferably in the range from 0.5: 1 to 5: 1, in particular from 0.8: 1 to 4: 1, particularly preferably in the range from 1: 1 to 1 , 5: 1.

The polymerization according to the invention can be carried out using a wide variety of methods, such as bulk, solution, emulsion or suspension polymerization. For example, melt polymerization, e.g. be carried out in an extruder or a kneader. Suitable solvents for the polymerization in solution are, for example, tetrahydrofuran, toluene, ethylbenzene or mixtures thereof.

The reaction conditions are generally not critical, the temperatures can be in the range from 0 to 220 ° C., preferably in the range from 20 to 180 ° C., usually one works at normal pressure, but one can also work at pressures up to 30 bar . The reaction times are preferably chosen so that polymerization is carried out until the desired molecular weight is reached, for example from 1 hour to 6 days. It may be advantageous to carry out the reaction under an inert gas, for example nitrogen or a noble gas such as argon.

The process according to the invention is preferably carried out by introducing the radical initiator and the radical I or a compound II and adding the monomer or the monomers and, if appropriate, the solvent. However, the reverse order of addition is also possible. If electron donors or N-oxyl radicals or mixtures thereof are used, these can be introduced together with the radical initiators and the radical I. However, they can also be added separately or individually in the course of the polymerization reaction. The polymers can be worked up by precipitation, for example in methanol or hexane.

The molecular weights M _n (number average) of the resulting polymers can vary within wide ranges, for example from 5000 to 500,000 g / mol.

In addition to homopolymers, statistical copolymers can also be produced by means of the method according to the invention. Statistical copolymers are expediently prepared by polymerizing the N-vinyl compounds together with suitable unsaturated monomers, in particular vinyl monomers.

Particularly suitable vinyl comonomers are olefins, vinyl chloride, vinylidene chloride, esters of vinyl alcohol and monocarboxylic acids with 1 to 8 carbon atoms, such as, for example, vinyl acetate, vinyl aromatics such as styrene, 2-vinyl naphthalene and 9-vinyl anthracene, substituted vinyl aromatics such as p- methylstyrene, α-methylstyrene, p-chlorostyrene, 2, 4 dimethylstyrene and 4 -Vinylbiphenyl, Ci to C ₈ alkyl esters of acrylic acid or methacrylic acid, particularly Ci to C ₄ acrylates and C - to _C4 methacrylates, unsaturated dicarboxylic acids, for example aliphatic unsaturated dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid, or their derivatives such as

Anhydrides, esters and amides, especially anhydrides, such as maleic anhydride, or vinyl cyanides, especially acrylonitrile. Mixtures of different comonomers can also be used.

Preferred comonomers are styrene, substituted styrenes, Ci to C ₄ acrylates and C _λ to C ₄ methacrylates, in particular methyl methacrylate, and acrylonitrile. The proportion of the comonomers is usually up to 80, preferably up to 50, particularly preferably up to 30% by weight, based on the copolymer obtained from N-vinyl compounds and comonomer.

In addition to the homo- and statistical copolymers described, the process according to the invention can also be used to produce segmented copolymers such as block copolymers, star block copolymers, graft copolymers or graft block copolymers by reacting the polymers further, preferably without working up, with other monomers or monomer mixtures of a different composition. The addition of further amounts of radicals I or compounds II, radical initiators, electron donors or N-oxyl radicals or mixtures thereof may be necessary.

Block copolymers can also be produced from the process according to the invention

at least one polymer block A obtainable by polymerization in the presence of radicals I from NVP homopolymer or NVP copolymer with up to 80, preferably up to 50% by weight, based on block A, of comonomers

and

at least one polymer block B obtainable by polymerization in the presence of radicals I from NVF homopolymer or NVF copolymer with up to 80, preferably up to 50% by weight, based on block B, comonomers,

wherein the polymer blocks A, B are connected directly and not by constitutional units which are not part of the blocks.

Preferred comonomers for blocks A and B are the vinyl comonomers mentioned above and the monomers mentioned below for block C.

If a polymer block of type A is symbolized with A and a polymer block of type B with B and if initiator, optionally moderator and termination residues are left out of consideration, the following are suitable as amphiphilic block copolymers according to the invention, for example: linear systems such as AB, ABA, BAA, BAB , ABB or (AB) _n , star-shaped systems such as A (B) _n , B (A) _n or (A) _n -BA- () _m , dendrimeric systems such as ((A) _n -B) _m A, (( B) _n -A) _m B, ((A) _m -B) _n A) _p B or ((B) _m -A) _n B) _p A or comb-shaped systems such as ((A) _n -A (B)) _g or ((B) _n -B (A)) _q , where m, n and p are integers from 1 to 5 and q is an integer from 0 to 1000.

Linear di- and triblock copolymers are also preferred according to the invention. If the sequence of the letters A, B represents the chronological sequence of the block production, block copolymers which are favorable according to the invention can be represented schematically as A-B, B-A, B-A-B and A-B-A.

So-called isophilic block copolymers can also be produced by the process according to the invention, that is to say block copolymers whose blocks consist of different monomers, but have a comparable or at least similar solubility in the same solvent. According to the invention, these isophilic block copolymers consist of

at least one polymer block A made of NVP homo- or copolymer, as already defined above

and or

at least one polymer block B made of NVF homo- or copolymer, as already defined above,

and

at least one polymer block C, obtainable by polymerization in the presence of radicals I of one or more hydrophilic monomers from the group consisting of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, 2-acrylamido-2-methylpropanesulfonic acid, styrene sulfonic acid, the potassium, Sodium and ammonium salts and the amides of the abovementioned acids, ω-hydroxy-C ₂ - to C ₄ -alkyl acrylate, ω-hydroxy-C ₂ - to C ₄ -alkyl methacrylate, vinyl imidazole, vinyl caprolactam, N-methyl vinyl imidazole, vinyl methyl ether and dimethylaminoethyl acrylate,

where the polymer blocks of types A, B, C are connected directly and not through constitutional units that are not part of the blocks.

The isophilic block copolymers therefore always contain block C and either block A or block B or blocks A, B and C. If a polymer block of type A is symbolized with A and a polymer block of type C with C and if initiator, optionally moderator and termination residues are not taken into account, amphiphilic block copolymers according to the invention are, for example, suitable: linear systems such as AC, ACA, CAA, CAC , ACC or (AC) _n , star-shaped systems such as A (C) _n , C (A) _n or (A) _n -CA- (C) _m , dendrimeric systems such as ((A) _n -C) _m A, ( (C) _n -A) _m C, ((A) _m -C) _n A) _p C or ((C) _m -A) _n C) _p A or comb-shaped systems such as ((A) _n -A (C )) _q or ((C) _n -C (A)) _q , where m, n and p are integers from 1 to 5 and q is an integer from 0 to 1000.

Linear di- and triblock copolymers are also preferred according to the invention. If the sequence of the letters A, C represents the chronological sequence of the block production, amphiphilic block copolymers which are favorable according to the invention can be represented schematically as A-C, C-A, C-A-C and A-C-A.

The same block sequences also apply mutatis mutandis to blocks B and C: in the above schematic block sequences, A must be replaced by B.

Block C can be linked to blocks A and B in any order, e.g. A-B-C, A-C-B, C-A-B, etc.

The following applies to all of the above-mentioned block copolymers from blocks A and B, or A and C, or B and C, or A, B and C: the block copolymers according to the invention (the term block copolymer here means polymers whose molecules consist of preferably linearly linked blocks exist, the blocks being directly connected to one another and the term block meaning a section of a polymer molecule which comprises several monomeric units which have at least one common feature which does not occur in the immediately adjacent sections) can be two-block copolymers, three-block copolymers or else multiblock copolymers comprising more than three blocks. They are preferably not networked.

Block copolymers according to the invention which are soluble in the aqueous medium should also include those which are not directly soluble in the aqueous polymerization medium, but whose dissolution can be brought about indirectly, for example, by first preparing them in a water-miscible organic solvent or in a Mixture of water and such an organic solvent dissolves (for example in dioxane, tetrahydrofuran or their mixtures with water) and this solution (which according to the invention can in part also be added directly to the aqueous polymerization medium) subsequently, for example via slide analysis or multiple addition of small amounts of water and subsequent separation by distillation of the organic solvent used ^¬ means converts into an aqueous solution (instead of water is often reasonable, an aqueous solution of an acid and / or base addresses). The term solution does not imply here necessarily a molecular solution, but only brings to the off ^¬ pressure that there is a clear liquid and in particular also includes micellar solutions, especially those that are not in thermodynamic equilibrium.

The block copolymers according to the invention generally have a radical at the chain end which is derived from the radicals I or from R ⁵ . Some of these residues can be replaced by a terminal oxyamine group. For various reasons, removal of the radicals I derived from radicals I may be desirable. In column 6, lines 54ff, US-A 4,581,429 offers various such removal options. Of particular interest according to the invention are those which lead to an -H, a hydroxyl group or an ethylenically unsaturated terminal group.

The process according to the invention is characterized in particular by economy, since the reaction proceeds sufficiently quickly at the technically interesting temperature range and the reaction rate can also be controlled well. The process according to the invention is largely insensitive to small amounts of moisture and mixtures of monomers can also be converted into statistical copolymers.

The use of the radicals I or

Compounds II leads to polymers with reactive "living" radical chain ends, so that a block copolymer or another copolymer such as star block copolymer, graft copolymer or graft block copolymer can be obtained by simply adding another radically polymerizable monomer (mixture) to the reactor. Isolation of the initially produced polymer with a living chain end is just as little necessary as the difficult and time-consuming "polarity reversal" of the reactivity center, as is known from classic block copolymerization. Block copolymers or other copolymers containing N-vinyl compounds can therefore be conveniently prepared in a "one-pot reaction" by the process according to the invention. The process according to the invention also allows the simple production of block copolymers from monomers which cannot be polymerized anionically and / or cationically. The resulting polymers of the N-vinyl compounds are free of heavy metals. The polymerized N-vinyl compounds and in particular polyNVP homopolymer, which is produced by the process according to the invention, are therefore particularly suitable for use in medicine. By adjusting the polymerization conditions, it is possible in particular to produce PolyNVP with a molecular weight that can pass through the human kidney. Such a PolyNVP is therefore suitable as a blood plasma substitute.

Examples

Commercially available benzoyl peroxide was used without further ^purification . 2,5-Dihydro-1, 3, 5, 5-tetraphenyl-1H-1, 2, 4, -tri-azol-2-yl was, according to Tetrahedron 51 (47), 12883-12898, 1995, by dehydrogenation of the corresponding 4th , 5-Dihydro-lH-l, 2, 4-triazole.

Comparative experiment: Polymerization of NVP without radical I

500 g of N-vinylpyrrolidone and 1 g of benzoyl peroxide were introduced as a free-radical initiator in a stirred tank reactor. After flushing with nitrogen gas, the mixture was heated to 130 ° C. with stirring and kept at this temperature for 5 hours. After cooling, the polymer obtained was precipitated by pouring the reaction mixture into cyclohexane and dried.

The polyNVP obtained had a weight average molecular weight of 120,000 g / mol; the polydispersity index PDI = weight average / number average was 8.4.

Attempt:

The procedure was as in the comparative experiment, except that 1.2 g of 1,3,5,5-tetraphenyl -2,5-di-hydro-lH-l, 2,4-triazol-2-yl Formula I ₃ with R ¹ to R ⁴ = phenyl) submitted.

The polyNVP obtained had a molecular weight (weight average) of 90,000, the polydispersity index PD) was 5.8.

The experiments show that the use of the radicals I according to the invention leads to poly-N-vinyl compounds with a lower polydispersity and a lower molecular weight.

Claims

claims

1. A process for preparing polymers of N-Vinylverbindun ^¬ gene, characterized in that mean the polymerization of N-vinyl compounds in the presence of radicals of the general formula I ^¬

> N '

I T (I), C.

Rl "^; N '

in which Q is NR ² or S and T is CR ³ R ⁴ or S and R ¹ , R ² , R ³ and R ^{4 can be} identical or different from one another and independently of one another hydrogen, Ci to C ₂ o ~ alkyl or C ₆ - to Cι ₈ aryl, carries out.

2. The method according to claim 1, characterized in that one or a radical initiator or an electron donor or their

Mixtures used.

3. Process according to claims 1 to 2, characterized in that the radicals used are I 2, 5-dihydro-1H-1, 2, 4-triazolyl radicals.

4. The method according to claims 1 to 3, characterized in that the radicals I from compounds II, which can be split into radical starters and radicals I, are generated.

5. Process according to claims 1 to 4, characterized in that 1-vinyl -2-pyrrolidone (N- vinyl pyrrolidone) or N-vinyl formamide or a mixture thereof is used as the N-vinyl compound.

6. Use of radicals I for the production of polymers from -Viny1verbindungen.

7. Use of the polymers prepared according to one of claims 1 to 5 from N-vinyl compounds for the production of blood plasma substitutes.

8. Polymers made of N-vinyl compounds, obtainable by the process according to one of claims 1 to 5.

9. Block copolymers, obtainable by reacting at least one polymer block A obtainable by polymerization in the presence of radicals I from N-vinylpyrrolidone homopolymer or N-vinylpyrrolidone copolymer with up to 80% by weight, based on block A, of comonomers

and

at least one polymer block B obtainable by polymerization in the presence of radicals I from N-vinylformamide homopolymer or N-vinylformamide copolymer with up to 80% by weight, based on block B, comonomers,

wherein the polymer blocks A, B are directly and not connected to one another by constitutional units which are not part of the blocks, by the process according to claims 1 to 5.

10. Block copolymers, obtainable by reacting

at least one polymer block A made of N-vinylpyrrolidone homo- or copolymer as defined in claim 9

and or

at least one polymer block B of N-vinylformamide homo- or copolymer as defined in claim 9

and

at least one polymer block C, obtainable by polymerization in the presence of radicals I of one or more hydrophilic monomers from the group consisting of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, 2-acrylamido-2-methylpropanesulfonic acid, styrene sulfonic acid, the potassium, Sodium and ammonium salts and the amides of the abovementioned acids, ω-hydroxy-C ₂ - to C ₄ -alkyl acrylate, ω-hydroxy-C ₂ - to C ₄ -alkyl methacrylate, vinylimidazole, vinylcaprolactam, N-methylvinylimidazole, vinyl methyl ether and dimethylaminoethyl acrylate ,

wherein the polymer blocks of the types A, B, C are connected directly and not by constitutional units which are not part of the blocks, according to the process according to claims 1 to 5.